Recently, fields of optical communication and optical information processing using optical techniques as well as fields of electronic equipment and optical equipment have rapidly developed, and it is an important problem to develop techniques for connecting various types of optical devices. Conventionally, the optical devices of various types are connected to each other through an optical wiring such as an optical fiber or the like. For such connection, quite high positional accuracy is required. Since an operation for such connection is carried out either manually or by means of highly accurate alignment equipment, the operation has disadvantageously caused an increase in connection cost.
In order to solve this problem, a technique for a self-organizing optical waveguide has been developed. According to this technique, an end of an optical wiring or the like to be connected to an optical device is immersed in a photosensitive composition, and a photosensitive material is irradiated with light through this optical wiring or the like. The photosensitive material is thereby gradually photosensitized and a core part of an optical waveguide is formed on a tip end of this optical connection end. Thereby, even without particularly expensive alignment equipment, an optical waveguide constituted to be able to transmit an optical signal between the optical wiring and the optical device can be formed, and the problem that causes the increase in connection cost can be solved.
Such a self-organizing optical waveguide formation technique will be briefly described with reference to the drawings. FIGS. 39(a) to 39(d) are schematic diagrams for describing one example of a method of forming the core part of the optical waveguide that connects different optical fibers to each other using this self-organizing optical waveguide technique.
First, optical fibers 112 and 112′ are arranged such that one end of one optical fiber faces one end of the other optical fiber. A photosensitive composition 111 is applied so as to surround the ends of the optical fibers 112 and 112′, whereby the ends of the optical fibers 112 and 112′ are both immersed in the photosensitive composition 111 (see FIG. 39(a)). In FIG. 39(a), 113 and 113′ represent cores of the respective optical fibers 112 and 112′.
Means (not shown) for irradiating light such as light of a high pressure mercury lamp is provided on the other end of one optical fiber 112 which does not face the other optical fiber 112′, and light for curing the photosensitive composition 111 is irradiated from one end of the optical fiber 112 toward one end of the optical fiber 112′ arranged to face one end of the optical fiber 112 using this means (see FIG. 39(b)).
By irradiating the light from one end of one optical fiber 112 to that of the other optical fiber 112′, the photosensitive composition 111 is gradually cured from an optical fiber 112-side correspondingly to an optical path, and the core part 114 of the optical waveguide that connects the optical fiber 112 to the optical fiber 112′ is formed (see FIG. 39(c) to FIG. 39(d)).
Furthermore, due to the development of the fields using the optical techniques such as the optical communication and the optical information processing, attention has been focused on optical fibers mainly in communication fields. Particularly in the IT (Information Technology) field, an optical communication technique employing the optical fibers is necessary to provide a high speed Internet network.
The optical fiber has features: (1) low loss, (2) high band, (3) small diameter and light weight, (4) non-induction, (5) resource saving, and the like. A communication system which employs the optical fibers having these features can considerably decrease the number of relays as compared with a communication system which employs conventional metallic cables, can be easily constructed and maintained, and can improve its economical development and reliability.
Further, since the optical fiber can transmit not only light having a single wavelength but also light having many different wavelengths simultaneously, i.e., only one optical fiber can provide multiple transmission of light having many different wavelengths, it is possible to realize a large capacity of a transmission path capable of dealing with diversified purposes and to deal with picture service and the like.
Emission light emitted from an optical component such as a semiconductor laser is incident on such an optical fiber. It is an important element in the optical communication how efficiently the emission light is caused to be incident on the optical fiber. In long-distance transmission, in particular, it is required to cause the emission light to be incident on the optical fiber with high efficiency.
However, it is necessary to provide a gap between the optical fiber and the optical component for the purpose of preventing the optical fiber from being damaged due to a thermal expansion of the optical fiber or the like. The gap is, therefore, a hindrance for realizing the efficient incidence of the emission light on the optical fiber.
To avoid this problem, a method of causing the emission light of the optical component to be incident on the optical fiber by providing a lens such as a collimator lens or a condensing lens between the optical component and the optical fiber is used. With this method, even if the gap is provided between the optical component and the optical fiber, the emission light of the optical component can be caused to be efficiently incident on the optical fiber.
This method can be used for not only transmitting the light from the optical component to the optical fiber but also transmitting a light from the optical fiber to the optical component and transmitting light from one optical fiber to the other optical fiber. With this method, efficient light transmission can be achieved in any of these cases.
Furthermore, following the development of the fields using the optical techniques such as the optical communication and the optical information processing, performances of various types of optical communication devices have been enhanced, thereby disadvantageously complicating connection between the devices for optical communication.